Rationale

In 2017 the “Standard Test Method for Uniaxial Pre-strain and Thermal Free Recovery of Shape Memory Alloys” was published for the first time as E3098. Since its publication several revisions have been suggested and tracked. This work item intends to ballot the suggested revisions. Furthermore, the test method is due for balloting. The suggested revisions and rationale are summarized as follows:

Revision: Mechanical removed from title.
Rationale: Redundant and implied by Uniaxial Pre-strain

Revision: Editorial changes to scope statement.
1.1 This test method describes the heating and coolingthermal cycling of a Shape Memory Alloy (SMA) specimen through the phase transformation under minimal load transformation after uniaxial deformation. This method will measure to determine residual strain after loading and unloading, recovered strain on heating, total unrecovered strain upon cooling, and transformation temperatures. This test is done to provide data for the selection of SMA materials, quality control, design allowables and actuator design.
Rationale: To clarify without changing intent

Revision: Definitions removed, Reference to E3097 added
Rationale: E3097 was not published yet when E3098 was released. The two test methods have overlapping definitions. A revision to E3097 was recently published. Overlapping definitions are captured in E3097 and removed from E3098

Revision: Figure 2 and 3 moved forward of Figure 1
Rationale: To reflect order in which they are referenced.

Revision: User or program now specifies Lower Cycle Temperature (LCT) and Upper Cycle Temperature (UCT)
The LCT and UCT shall be defined by the program and shall be in accordance within the limits in the terminology of Paragraphs 6.7 and 6.8. If a LCT or UCT is not defined it shall be determined by test in accordance with Paragraphs 6.7 and 6.8.
Rationale: After several years of use, this is how the test method is typically being used. An Inter-Laboratory Study (ILS) is currently being conducted and specifies LCT and UCT.

Revision: 5.1 A material's martensitic stress-strain response, martensite residual strain, austenite recovered strain, and unrecovered strain (or plastic deformation) after thermal cycling is determined.
Rationale: “stiffness” replaced with “stress-strain response”. The martensite loading curve is non-linear. The term stiffness can be misleading.

Revision: 5.4 This test method can be used on trained and processed material in a semi-finished form to measure Two Way Shape Memory Effect (TWSME) by comparing the strain in the austenite state and martensite states with no applied minimal applied stress. The force is set to a minimum value not to exceed a corresponding stress of 7 MPa (in accordance ASTM F2516).
Rationale: “no applied stress” replaced with “minimal applied stress”. To be consistent with other test methods. There is typically some stress applied in order to remove mechanical play in the load frame.

Revision: Added Reference. (6) Benafan, O., Bigelow, G. S., & Wood, L. (2019). Ruggedness Evaluation of ASTM International Standard Test Methods for Shape Memory Materials: E3097 Standard Test Method for Mechanical Uniaxial Constant Force Thermal Cycling of Shape Memory Alloys. NASA/TM-2019-220029
Rationale: Reference includes ruggedness test data generated after the first publication of E3097-17